The present invention relates to a fluid pump for feeding liquid such as blood or medical fluid by sequentially compressing one or more pump tubes, and more particularly to a conical fluid pump including a pump body, a rotor shaft rotatably supported in the pump body, a roller holder mounted on the rotor shaft, a plurality of roller shafts mounted about the periphery of the roller holder such that the axes thereof converge on the axis of the rotor shaft, and a plurality of tapered rollers each rotatably mounted on the roller shaft and having a tapered surface, the envelope defined by the tapered rollers forming a frustoconical shape, also converging on the axis of the rotor shaft said tapered rollers being adapted to sequentially compress the pump tubes in a manner to feed fluid therethrough.
Such a conical fluid pump is disclosed in Japanese Patent Application No. 167630/1981 (Japanese Laid Open Patent Application No. 69570/1983).
In the above-mentioned Japanese Patent Application, the roller shafts and the tapered rollers are inclined in an inward converging fashion, and a guide tube is compressed between the tapered rollers and a complementary tapered inner surface which is formed in a lower half of a conical head and which is secured to the pump body. By providing tapered rollers in place of conventional cylindrical rollers, the urging force on the pump tube can be easily regulated by varying the axial position of the roller holder relative to the conical head.
However, as the tapered rollers incline inwards, the pump tube can be replaced only after removing the roller holder with the tapered rollers from the rotor shaft.